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Re: Why not NiMH?

From J Burns <burns4@nowhere.com>
Newsgroups comp.sys.mac.system
Subject Re: Why not NiMH?
Date 2013-12-06 13:19 -0500
Organization A noiseless patient Spider
Message-ID <l7t4f7$1vd$1@dont-email.me> (permalink)
References <l7o6ih$a9r$1@dont-email.me> <l7q1p9$6us$1@dont-email.me> <l7qdvh$nml$1@dont-email.me> <mcmurtrie-1984CE.22445505122013@c-61-68-245-199.per.connect.net.au>

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On 12/6/13 1:44 AM, Kevin McMurtrie wrote:
> In article <l7qdvh$nml$1@dont-email.me>, J Burns <burns4@nowhere.com>
> wrote:
>
>> On 12/5/13 9:15 AM, Király wrote:
>>> J Burns <burns4@nowhere.com> wrote:
>>>> For several months, I've been using Eneloop AA NiMH cells.  They vastly
>>>> better.  I can count on them for a device that requires 1500ma.  They
>>>> take only an hour to charge and always seem to charge fully, about
>>>> 2,000mah.  They're supposed to be good for 1500 cycles
>>>
>>> Not if you're pumping 2 amps through them to charge them in an hour. You
>>> will drastically reduce their life if you do that. You'll get closer
>>> to the published 1500 cycle life if you charge them at a low current
>>> over a longer time, like 200ma over 10 hours.
>>>
>> NiCd manufacturers used to recommend C/10 for 14 hours.  My first set
>> was GE cells with a GE charger.  Instead of 500 cycles, I got about 50.
>>
>> When I went to NiMH, manufactures said C/10 wouldn't work.  I got a
>> charger that worked in about 2 hours.  After 10 years and hundreds of
>> cycles, 8 cells of 2 brands were still going strong.
>
> You can only detect a full charge in NiMH using voltage depression when
> charging near the C/3 to C rate.  Other rates require other methods that
> aren't as accurate.  Repeated undercharging is fine, but too much
> overcharging ages the battery.
>
Thanks.  I see overcharging at C/10 is supposed to be okay for NiCd, but 
C/20 should be the limit for overcharging NiMH.  I've read that it may 
be better to undercharge than to fool with overcharging.

I used to check capacity with a 1.5V analog clock in parallel with a 
resistor.  The capacity of a NiCd could stay good for years, but 
self-discharge would get bad.  I didn't see that after I went to a fast 
charger.

A NiMH that had sat idle for weeks or months would show reduced capacity 
and high internal resistance.  Apparently the electrolyte wasn't evenly 
distributed.  It was likely to improve with each cycle. I imagine it's 
less of a problem with some of the newer NiMH cells.

I've read that if a cell heats up while charging, the charger may not 
detect a voltage drop when it's charged.  I've had that happen at least 
once.  The charging light stayed on and the cell got unusually hot.  So 
far, the Eneloops have stayed cooler than cells in the past while charging.

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Thread

Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-04 16:24 -0500
  Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-04 16:38 -0500
    Re: Why not NiMH? dorayme <dorayme@optusnet.com.au> - 2013-12-05 11:01 +1100
      Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-04 23:38 -0500
        Re: Why not NiMH? Mike Lane <mike.lane.usenet@ntlworld.co.uk> - 2013-12-05 13:21 +0000
          Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-05 11:29 -0500
          Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-06 09:01 +1300
      Re: Why not NiMH? Davoud <star@sky.net> - 2013-12-05 05:21 -0500
        Re: Why not NiMH? dorayme <dorayme@optusnet.com.au> - 2013-12-06 09:07 +1100
          Re: Why not NiMH? Davoud <star@sky.net> - 2013-12-05 18:42 -0500
            Re: Why not NiMH? dorayme <dorayme@optusnet.com.au> - 2013-12-06 11:57 +1100
              Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-06 18:34 +1300
                Re: Why not NiMH? dorayme <dorayme@optusnet.com.au> - 2013-12-06 17:08 +1100
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-06 19:19 +1300
                Re: Why not NiMH? dorayme <dorayme@optusnet.com.au> - 2013-12-06 20:14 +1100
          Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-06 13:30 +1300
            Re: Why not NiMH? dorayme <dorayme@optusnet.com.au> - 2013-12-06 12:00 +1100
              Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-06 18:24 +1300
            Re: Why not NiMH? George Kerby <ghost_topper@hotmail.com> - 2013-12-05 19:50 -0600
      Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-05 15:11 -0500
        Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-05 16:15 -0500
    Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-04 19:59 -0500
      Re: Why not NiMH? Ted Lee <tmplee@mr.net> - 2013-12-04 22:09 -0600
        Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-04 23:38 -0500
        Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-05 00:54 -0500
          Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-05 00:59 -0500
            Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-05 02:22 -0500
              Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-05 02:44 -0500
                Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-05 03:36 -0500
                Re: Why not NiMH? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2013-12-05 04:21 -0500
                Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-05 11:29 -0500
                Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-05 16:24 -0500
              Re: Why not NiMH? Jolly Roger <jollyroger@pobox.com> - 2013-12-05 18:37 +0000
                Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-05 14:19 -0500
                Re: Why not NiMH? George Kerby <ghost_topper@hotmail.com> - 2013-12-05 13:31 -0600
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-06 09:07 +1300
                Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-05 14:36 -0500
                Re: Why not NiMH? Jolly Roger <jollyroger@pobox.com> - 2013-12-05 22:02 +0000
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-06 13:26 +1300
                Re: Why not NiMH? Jolly Roger <jollyroger@pobox.com> - 2013-12-06 00:33 +0000
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-06 18:36 +1300
                Re: Why not NiMH? Jolly Roger <jollyroger@pobox.com> - 2013-12-06 21:22 +0000
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-07 11:49 +1300
                Re: Why not NiMH? Jolly Roger <jollyroger@pobox.com> - 2013-12-07 00:11 +0000
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-07 18:07 +1300
                Re: Why not NiMH? George Kerby <ghost_topper@hotmail.com> - 2013-12-07 08:37 -0600
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-08 09:52 +1300
                Re: Why not NiMH? George Kerby <ghost_topper@hotmail.com> - 2013-12-05 19:49 -0600
                Re: Why not NiMH? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2013-12-05 21:55 -0500
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-06 18:40 +1300
                Re: Why not NiMH? Jolly Roger <jollyroger@pobox.com> - 2013-12-06 21:24 +0000
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-07 11:49 +1300
                Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-06 18:43 -0500
                Re: Why not NiMH? George Kerby <ghost_topper@hotmail.com> - 2013-12-07 08:32 -0600
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-08 09:50 +1300
                Re: Why not NiMH? George Kerby <ghost_topper@hotmail.com> - 2013-12-07 15:50 -0600
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-08 14:04 +1300
                Re: Why not NiMH? George Kerby <ghost_topper@hotmail.com> - 2013-12-07 21:02 -0600
                Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-08 17:45 +1300
                Re: Why not NiMH? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2013-12-06 17:48 +0000
                Re: Why not NiMH? Jolly Roger <jollyroger@pobox.com> - 2013-12-06 21:25 +0000
        Re: Why not NiMH? Davoud <star@sky.net> - 2013-12-05 05:33 -0500
        Re: Why not NiMH? Jolly Roger <jollyroger@pobox.com> - 2013-12-05 18:35 +0000
      Re: Why not NiMH? Zar Zifodow <zarzifodow@mailinator.com> - 2013-12-04 20:14 -0800
      Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-04 23:38 -0500
        Re: Why not NiMH? Siri Cruz <chine.bleu@yahoo.com> - 2013-12-04 20:46 -0800
        Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-05 02:22 -0500
          Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-05 02:44 -0500
  Re: Why not NiMH? Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2013-12-04 23:08 -0800
    Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-05 03:08 -0500
      Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-05 11:29 -0500
  Re: Why not NiMH? me@home.spamsucks.ca (Király) - 2013-12-05 14:15 +0000
    Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-05 12:43 -0500
      Re: Why not NiMH? nospam <nospam@nospam.invalid> - 2013-12-05 12:54 -0500
      Re: Why not NiMH? Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2013-12-05 22:44 -0800
        Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-06 13:19 -0500
      Re: Why not NiMH? me@home.spamsucks.ca (Kiraly) - 2013-12-06 22:35 +0000
        Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-07 02:27 -0500
        Re: Why not NiMH? J Burns <burns4@nowhere.com> - 2013-12-08 00:10 -0500
  Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-14 18:57 +1300
    Re: Why not NiMH? Fred Moore <fmoore@gcfn.org> - 2013-12-17 12:04 -0500
      Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-18 09:27 +1300
  Re: Why not NiMH? Your Name <YourName@YourISP.com> - 2013-12-19 18:59 +1300

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